555 Market Street SF
Seismic retrofit of a 23-story composite steel and concrete framed office tower originally designed in 1964. The tower was strengthened to conform to San Francisco Building Code for existing buildings with certain exceptions. The retrofit included selective strengthening of the reinforced concrete walls in the lower stories of the tower, seismic collector strengthening, and the addition of horizontal bracing at the low roof to carry tower seismic loads to concrete walls. Collapse prevention performance criteria of FEMA 356 were employed to demonstrate adequacy of the final retrofit design via push-over analyses. The use of performance-based procedures minimized the extent and cost of retrofit work.
DivcoWest Properties (Equity Office Properties – current ownership)